Gaseous conduction apparatus



Oct. 31, 1933. c. G. SMITH GASEOUS CONDUCTION APPARATUS Filed Oct. 29, 1928 INVENTOR Patented Oct.31,1933 \v 1,933,396

UNIT-ED" PATENT QFFICE Gaseous ooNnUo'rroN APPARATUS.

Charles G. S mith, Medford,' Mass, assignor to Raytheon, Inc., Cambridge, Mass, a corporation of Massachusetts 1 Applicatien ctober 29, 1923. Serial No."315 ,8 67

' 4 Claims..(Cl. 250 -27.5)'

My invention'relates to gaseous conduction apa metallic capsule containing the metal or. com paratus and especially to rectifiers. In my prior pounds which will liberate the metal, near the Patent 1,617,179, granted February 8,1927, as wel l region of discharge so as to be warmed thereby. as other patents and applications, I have dis- However, it hasbeen found that small amounts of 5 closed a rectifier in which an anode and a surthe metal will condense near the capsule and rounding cathode in-a gas cooperate to rectify alcause-the discharge to go to.that spot.- The disternating current. In an application of Bush, charge will thus be"continuouslymovingover the Serial No. 22,988, filedApril 14, 1925, assigned surface always after concentrated amounts ofto the same assignee as thisc'ase, is disclosed a metal. This. causes the region of discharge to modification of the rectifier of the-patent referred beobjectionably close to the source of vaporand to. The 'Bush type of rectifier'has an enclosing results in an unnecessary large evolution of such," cathode with two anodes in theenclosedregion, vapor. a

U Such a tube when properly connected will rectify A further objectof my invention,-therefore,- is both waves of an alternating current,-thus form-1 to devise a rectifier having'asource of alkali or ing a'full wave rectifier. Rectifiers have also been alkaline earth metal vapor within it so disposed 70. devised in which a solid partition divides a caththat it is near enoughto the region of discharge ode region into two regions withan anode to each to be maintained at a desirable temperature, yet,

region. The advantage of the Bush type of recwithout causing the region ofdischarge to aptifier over this latter type is the fact that the proach said source.

I former starts on a much' lower. potential and 'Referring to the drawing, Figure 1 is an eleva- 75.

operates withless losses. The latter type of rection View ofa rectifier embodying my invention. 7 tifier is merely two single wave rectifiersin-one Figure 2;is-a view on line 2 of Figure llookenvelope, whereas the former type is more than ing upwards.

that. ,When suitably connected, there is ordi- The rectifier comprises a glass. envelope-1 with narily twice the difference in potential across the a reentrant press .2 terminating intubular mem- 80.;

anodesas between each anode and cathode. bers 3. Over tubular members 3, are insulators I-Ience on starting, thetube has the benefit of a 4 of lava or any other suitable material. These much higher starting potential than wouldorinsulators are fitted over tubular members 3 andv dinarily be the case. Furthermore-whenthe disat their free ends have enlarged annular regions charge between one anode and the cathodehas 5 cutout. Sealed in press 2 are lead wires 6 and 85,

been initiated, ions andelectrons wanderout- '7, which go into a base 8, suitably cemented to sidethe region" of dischargeadjacent the other the tube, and connected to suitable prongs of the anode and thus aid in the initiation, of the disbase. Leads 7 are led through tubular members charge between the other anode and cathodeon -3 and have at their ends small cylindrical anodes reverse cycle. With this type of construction, it 9 projecting through insulators 4. Anodes. 9 may. 90. has been found, however, that due to the unre be of any suitable material such as carbon, stricted space in which the two anodes are posinickel, .or tantalum, and as shown,; are snugly tioned, so many ions are produced near the-infitted into. insulators 4 and having their free active electrode thatan undesirably large back ends beyond said insulators. It will be noted I 40 current exists. I that annular regions 5 are slightly larger than 95 It is an object ofmy invention to attain the the cross sectional area of anodes 9. These advantages of the Bushytype of rectifier without regions 5 are of the order of the mean free path at the'same time allowing considerable back ourof the gas with which the tube is filled and serve rent. Another object'is to-attain the above object to protect the insulators from bombardment.

with simplicity of structure whichwillnot make Lead 6 is suitably connected to a dished member loo therectifier any more expensive to manufacture. 10. This member has its edges turneddown into Such types of rectifiers ordinarily have the va--v regions 5 so that it is maintained in place by r por of an alkali ,or alkaline earth metal vapor insulators 5. The outer edge of dished member present inorder to. reduce the losses through the .10 carries acylindrical memberll. This entire .5 tube. In'the case of metals like potjassiumand assembly .may further be strengthened by two 105 sodium which have a relatively low vapor presor morewires sealed in press 2. Dished member sure at ordinarytemperatures, it is necessary that 10 and cylindrical member llmay be made of the source from whichsuch vapor issues, shall any suitable metal adapted to be used as a be warm in order to obtain the desired vapor prescathode. Preferably they are made of nickel, the

sure. In each case it is customary to dispose inside surfaces of whichmay be suitably treated llQ its with oxides of alkaline earth metals if desired, so that electron emission may be easily obtained.

In order to prevent undesirable migration of ions from the region around one anode to that around the other anode I dispose a wire mesh 13 in such a manner that the anodes areseparated from each. other. This mesh may be of any suitable metal such as nickel or iron and is preferably of a fineness of around 200 spaces to the inch. This mesh may be suitably supported by being welded to dished member 10.

Mesh 13 allows a sufficient number of ions to percolate through to the region in which the main discharge is to take place so that the discharge may be easily initiated. At the same.

time, back current is cut down so that it is negligible.

In order that anodes 9 may be as close as possible to mesh 13, without making the tube as a whole unduly small, I make the entire cathode member of oblate shape as shown in Figure 2. The losses through the tube are lower by sucha construction. However, it is to be clearly understood that this shape of cathode is not necessary and a round cathode of usual design may be used if desired.

The top of the cathode carries a screen '12 which may be of the same material as 13. Above this screen is a dome or cap member 30 carrying a capsule 14. The cathode is thus entirely enclosed.

The tube is exhausted and freed of occluded gases as usual and thereafter filled with one or more of the rare gases to a pressure at about 6-8 mm. Preferably helium is used. Thereafter the tube is sealed. Capsule 14 is bombarded causing the-chemicals within it to be heated so that interaction occurs. The vapor of alkali or alkaline earth metal is released therefrom through minute holes or suitable openings and settles down through screen 12 on the inner surface of the cathode. The metal used is preferably potassium.

During the operating of the tube, the heat of the discharge is sufficient to warm up the region adjacent to capsule I l so that a sufficiently great vapor pressure of alkali metal is maintained.

The dome or cap 30 completely covers the top of the cathode and prevents escape of vapor dis-' charge. Screen 12 prevents the discharge irom enlarging and approaching too close to capsule While I have shown only two anodes, it, is obvious that my invention is applicable to tubes containing a greater number of anodes. Between adjacent anodes, there will preferably be a mesh similar to that shown and acting in the same manner. Thus it will be seen I have devised a tube in which a plurality of anodes may operate in a communicating space with all attendant advantages without at the same time having the disadvantage of a large back current. Furthermore, I have also devised a tube in which suitable vapor to reduce the potential drop may be introduced within the discharge region without enlarging the region of discharge beyond set limits. 7

I claim: v 1. A unidirectional space current device comprising a hermetically sealed vessel containing a relatively small-area anode, a relatively largearea cathode, enclosure means providing in conjunction with said cathode and anode an enclosure around the space between said cathode and said anode and segregating it from the space bordering the walls of said vessel, a source of ionizable gas in said enclosure for sustaining a space discharge between said cathode and said anode, and a screen in said enclosure for segregating and holding away the discharge from said source,'while permitting gas from said source to enter the discharge space.

2. A unidirectional space current device comprising a hermetically sealed vessel containing a relatively small-area anode, a hollow cathode of relatively large interior electrode area enclosing the space around said anode and segregating it from the space bordering the walls of said vessel, a conducting vaporizable body carried by said cathode in the interior thereof for supplying a vapor adapted to sustain a discharge between said cathode and said anode, and a screen in said-hollow cathode for segregating and holding away-the discharge from said vaporizable body, while permitting the vapors from said body to enter the discharge space. a

3. A unidirectional space current device comprising a hermetically sealed vessel containing a hollow conducting member having partition meanssubdividing the hollow space into a plurality of compartments having each a large-area interior cathode surface, small-area anodes enclosed in said compartments to maintain unidirectional discharges with said cathode surfaces,'said hollow conducting member segregating the space within its interior from the space bordering the walls of said vessel, a conducting vaporizable body carried by said hollow member in the interior thereof for supplying a vapor to said compartments adapted to sustain discharges between said anodes and said cathode surfaces, and a1 interior cathode surface, small-area anodes enclosed in said compartments to maintain unidirectional discharges with said cathode surfaces, said hollow conducting member segregating the space within its interior from the space bordering the walls of said vessel, a conducting vaporizable body carried by said hollow member in the interior thereof for supplying a vapor to said compartments adapted to sustain discharges between said anodes and said cathode surfaces, and a screen in said hollow member for segregating and holding away the discharge from said vaporizable body while'permitting the vapors from said body to enter the discharge space, the partition means between said compartmentshaving openings of a size preventing the discharge in one compartment a from extending into the adjacent compartment while securing ionizing action of the anode in one compartment on the content of the other com-- partment.

CHARLES G. SMITH.

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